Calculating machine



May 4, 1954 J. M, LAIHO CALCULATING MACHINE l0 Sheets-Sheet 1 Filed Dec.5, 1951 OOOOQGOOO OOOOOOGQO OOGOQGOGQ OOQOOOGOG H- .OQOQOOOGO gm 6T IiHVVENTOR. Jalmerf l [@1720 BY M 45' (31550 xzgys May 4, 1954 J. M. LAIHOCALCULATING MACHINE 1O Sheets-Sheet 3 Filed Dec. 5, 1951 INVENTIOR.JalmerM, Ida/Z0 Czii orrz e gs May 4, 1954 J. M. LAlHO CALCULATINGMACHINE l0 Sheets-Sheet 4 Filed Dec. 5, 1951 IN V EN TOR.

liner/14. Zaj/zo y 4 J. M. LAIHO CALCULATING MACHINE 10 Sheets-Sheet 5Filed Dec. 5, 1951 INVENTQR. JalmerM. Laz/w May 4, 1954 J. M, LAIHOCALCULATING MACHINE Filed Dec. 5, 1951 10 Sheets-Sheet 6 1 1 1 l l 'i 21 I l w. M ml HAUL? will I H W a; 4 0 (85 312 H Z INVENTOR. jJaZnzerMjai/w May 4, 1954 J. M. LAlHO 2,677,500

CALCULATING MACHINE Filed Dec. 5, 1951 10 Sheets-Sheet '7 INVENTQR.JaZmer/Vl. [cu/Z0 BY g CZZZorrzqys May 4, 1954 J. M. LAlHO CALCULATINGMACHINE Filed Dec. 5, 1951 10 Sheets-Sheet 8 INVENTOR.

I JZzZme/LM. lad/20 CZL'Zarrz qys May 4, 1954 J. M. LAIHO CALCULATINGMACHINE 10 Sheets-Sheet 9 Filed Dec. 5, 1951 INVENTOR.

May 4, 1954 Filed Dec. 5, 1951 J. M. LAIHO CALCULATING MACHINE l0Sheets-Sheet INVENTOR.

I JaZnzenM. Zczi/w Cliiorrzqzys Patented May 4, 1954 UNITED STATESPATENT OFFICE CALCULATING MACHINE Application December 5, 1951, SerialNo. 259,929

30 Claims. 1

This invention relates in general tocalculating machines, and moreparticularly to normally key-responsive calculating machines havingunidirectional accumulator actuating mechanism.

Briefly, the principal object of the instant invention is to facilitatethe performance of all types of calculations with such machines, andparticularly the repeat forms of calculation, such as division andmultiplication.

With prior machinesof this type, such as that shown in United StatesLetters Patent No. 2,063,962, issued December 15, 1936, and generally insubstantially all machines having actuating mechanism adapted to drivethe register or accumulator mechanism in one direction only, subtractionis performed by a process of complemental addition, the digit keys beingprovided with suitable indicia designating both their true values andthe nines complement-s thereof, and selectively operable carry cut-cutmechanism being included, as is well understood in theart, to enablesuch operations. Multiplication is accom plished with such machines byrepeated depressions of digit keys representing the multiplicand, withthe necessary lateral shifting of such operation to the denominationalorders dictated by the multiplier, and the performance of divisionrequires generally similar operations, using the complemental digitindicia, and governed by somewhat more complicated rules of procedure.

The performance of subtraction with such machines has been simplified bythe mechanism disclosed in my prior United States Letters Patent No. 2,l10,823, issued November 12, 1946, wherein the complemental marking ofthe digit keys is dispensed with, and the operator may proceed in amanner similar to that employed in longhand subtraction and withmachines having reversible actuator mechanism. This is accomplishedinthe machine of Patent No. 2,il0,823 by the provision of normallyinoperative complemental stop bars, subtraction control means includinga minus key settable to render the complemental stop bars operative andto render the normally key-responsive actuating mechanism lacy-set, andanother control means manually operable by depression of an equals key,after the depression of those digit keys representing a subtrahend, tocause actuation of the machine to enter the true complement of suchsubtrahend in the accumulator, including the automatic entry of 9s inall denominational orders in which no digit keys were depressed and cl10 in the units order if no digit key was depressed therein. Sincedepression of this equals key also causes automatic return of thesubtraction control means and the minus key to normal inoperativeposition, to condition the machine for additive actuations, theperformance of problems in division is not facilitated with the machineof Patent No. 2,410,823.

Simplified means for performing division therefore were incorporated insuch a-calculating machine, in addition to the subtraction mechanism ofPatent No. 2,410,823, as fully illustrated and disclosed in my .priorUnited States Letters Patent No. 2,492,703, issued December'27, 1949,and No. 2, l3u575, issued November 11, 1947. These latter machinesinclude division mechanism settable to cause the entry of the truecomplement or a divisor into the accumulator, upon depression of thedigit keys representing the actual figures of the same, as Well as aresultant automatic entry of 9s inall denominational orders where nokeys Were depressed to the right only of the leftmost or highest orderof the divisor, except in the units order, in which 10 is added if nodigit key was depressed therein. However, they require repeated manualdepressions of those digit keys representing the divisor, including thelateral or trans-denominational shifting by the machine operator of theparticular finger-holding corresponding to such divisor, as determinedby the specific problem being performed. Similar repeated depressions ofa plurality of digit keys representing 'a multiplicand, in accordancewith the digital values of a multiplier, including lateral ortransclencminational shifting of the particular fingerholdingarrangement dictated by the specific multiplicand, likewise are requiredin performing multiplication problems in all of the prior machines,hereinbeiore enumerated.

In my prior United States Letters Patent No. 2,439,574, issued November11, 1947, I have provided means to facilitate the performance of repeattypes of calculations, namely, multiplication and division, inkey-responsive machines, which comprises manually settable mechanism forconditioning the machine for key-set crank operation, whereby thosedigit keys which are depressed to represent a multiplicand or divisorare retained in partially depressed position for subsequent completedepression, I'or the desired number of times, in response to actuationof an operating crank. In this prior machine of Patent No. 2,430,574,manual control members also are provided which are selectively operableto effect lateral shifting of the divisor 0r multiplicand keg/settingfrom one denominational position on the keyboard to a denominationallyadjacent position thereon in either direction, depending upon whetherdivision or multiplication is being performed. However, since themachine of Patent No. 2,430,574 has no complemental stop bar or digitalcontrol mechanism, it requires division to be performed in similarmanner to its performance with the older mechanism of Patent No.2,063,962, dispensing only with the previously required finger-holdingof the divisor complement.

A principal object of the instant invention is to provide a calculatingmachine of the normally key-responsive type, having unidirectionalactuating mechanism, in which the performance of repeat types ofcalculations is greatly facilitated, and this is accomplished byemploying some of the mechanism of the prior machines referred tohereinbefore and by adding other novel mechanisms which both makepossible the use of such old mechanisms and further simplify the Work ofthe operator. More specifically, the performance of problems of additionand subtraction is accomplished. in the same manner as in my priorPatent No. 2,410,823, but the performance of problems in multiplicationand division has been greatly simplified in comparison with the methodsrequired to be used in any of the machines of the cited patents. Withthe machine of the instant invention, multiplication is performed simplyby conditioning the machine for such operation by depressing a suitablemultiplication control key, entering the multiplicand on the keyboard,and repeatedly adding the multiplicand into the accumulator in responseto repeated depressions of an operations control key and of a singleshifter key for shifting the multiplicand keyboard setting to differentdenominational positions, both as dictated by the value of themultiplier. Problems in division similarly may be performed by use of adivision control key, instead of the multiplication control key, and thesame operations control key and shifter key.

Another important object of the invention is to eliminate thepossibility of misoperation of an optionally key-responsive or key-setcalculating machine by providing normally inoperative ordinal slide barsthat are moved to operative position, in response to the setting of themachine for key-set operation, to positively block and limit the degreeof movement which subsequently may be imparted to any digit key to anextent insufdcient to efiect key-responsive actuation of the machinethereby.

In my prior Patent No. 2,410,823, no such keyblocking means is employedwhen the machine is set for key-set actuation, the digit keys then beingpermitted their normal full extent of depressive movement. The functionof preventing resultant digital actuation of the accumulator in thatprior machine is performed by rotation of a transverse shaft by theminus key, which shaft carries a locking arm in each denominationalorder thus engaged with the actuator hook in that order that otherwisewould be engaged with the constantly rotating toothed Wheel of theactuator mechanism, upon digit key depression, so as to prevent suchhook and Wheel engagement when a digit key is depressed. The machine ofmy prior Patent No. 2,430,574 is always key-responsive in operation.Even though depressed digit keys are latched. in partially depressed orkey-set position for multiple types of calculation in the lattermachine, subsequent operation of the actuating mechanism is effected bycomplete depression of such keys, which is accomplished by rotating theoperations crank. In my other cited prior Patents No. 2,430,575 and No.2,492,703, the key-latching mechanism of No. 2,410,823 is employed forsubtraction calculations, and the machines are key-responsive inoperation when performing problems in division.

In the instant machine, however, the abovementioned normally inoperativeordinal slide bars are moved to operative position by depr sion of amultiple operations control key (either the division or themultiplication key), and then positively limit depressive movement ofany digit key to an extent less than that required to effect operationof the actuating mechanism. At the same time, normally inoperativekey-latching means are rendered operative to retain depressed digit keysin key-set position to determine the digital extent of subsequentoperations of the actuating mechanism. The latter operations areeffected by a manually depressible operations key.

Another object of this invention is to positively prevent operation ofthe actuating mechanism in such amachine, when the same is conditionedfor key-set operation, in response to excessively sharp or harddepression of the digit keys. Despite the positive limiting of thepermissible extent of movement of the digit keys by the ordinal slidebars, as enumerated above, which prevents key-responsive actuation innormal operation of the keys when the machine is conditioned for key-setoperations, the nature of the mechanism of this type of machine is suchthat the appli cation of an excessively sharp depressive force to adigit key can impart sufiicient momentum to its associated parallelmotion mechanism, or accumulator actuation initiating member, as toeffect operation of the accumulator actuating mechanism. Consequently,this object of the invention is attained by providing a normallyinoperative member in each denominational order, all of which are movedto operative position in response to depression of a multiple operationscontrol key for conditioning the machine for re peat forms ofcalculations, whereby such members are disposed in movement-blockingrelationship relative to their associated accumulator actuation-initiating members or parallel motion mechanism.

A further object of the invention is the provision of means forrendering these movementblocking members ineffective in response tosubsequent actuation of the operations control key. in order to permitproper operation of the accumulator actuating mechanism in response todepression of the operations control key.

Another object of this invention is the provision of such a calculatingmachine in ivhi multiple or repeated accumulator actuations may beefiected to perform both division and multiplication problems, after thespecific multiplicand or dividend and divisor have been set up in themachine, by use only of a depressible operations control key and, whenrequired, lateral or transordinal shifting of the keyboard settingrepresenting the divisor or the multiplicand by depression of a shifterkey, and in which these same two keys are used in both of these types ofmultiple calculations. The resulting simplification of the performance01 both positive and ne ative repeat forms of calculations in a machinehaving a uni-directional actuator is accomplished to a lar e extent byhaving each depression of such operations control key efiect operationor" the power trip bars in all denominational orders,

while rendering suchoperation of the :power trip bars inefiective to:actuate the accumulator during the performance of multiplicationproblems only, except in those denominational orders in which a digitkey has been depressed and latched in key-set position.

Thus a further object --of the invention is the provision, in acalculating machine :having a yieldable clutch interposed ibetweenapower actuated member .and a movement controlling .member or stop barand accumulator actuatorin each denominational order, the :digitalextent'of movement of the stop bar being determined by the digit keys,.of means actuated by depression of a multiplication control key forlooking all of 'the movement controlling members or ordinal stop barsagainst movement, such locking means thereafter being released in anydenominational order in which a digit key .is depressed. Morespecifically, these stop her locking means are connected to the ordinalslide bars which limit depressive movements of the digit keys, .and areengaged with their associated stop bars upon movement of the ordinalslide bars in one direction to operative position by the multiplicationcontrol key, and-disengaged from the stop bars upon movement oftheordinal slide bars in the opposite direction in lesser degree bysubsequent depression of an associated digit key. And, whiledepressionof the division controlkey also moves the ordinal slidebars toan intermediate position, such movement thereof is less than thatcheated by the multiplication control keyand insuflficient to causeengagement of this locking means with the stop'bars or movementcontrolling members.

A further object of the instant invention, therefore, is the provisionin such a calculating machine of normally inoperative ordinal slide barsthat are moved in'one'directionto an intermediate operative position bydepression of a division control key to positively limit subsequentdepressivemovements of the digit keys, and that are moved in the samedirection to a further extent to a second or fulloperative position bydepression of a multiplication control key, wherein subsequentdepression of the digit keys will move their associated ordinal slidebars in the opposite direction to such intermediate operative position.

Another object of this invention is to insure proper registration of thequotient in the accumulator in such a calculating machine when .divisionproblems are being performed. With the instant mechanism, as so fardescribed herein,

each subtraction of adivisor during-a division calculation isaccomplished by the depression of the operations control key andcomprises the addition to the dividend registrationin the accumulator oithe nines complement of each digit of the divisor, as set in thekeyboard, and the tens complement of the lowest or unitary digit of suchdivisor, together with the entry of 9s in all denominational orders ofthe machine higher than that iii-which the highest denominational digitof the divisor is located in such keybaord setting and in those'ordersin which no digit keys are depressed corresponding to zeros in the divisor. This is accomplished by automaticallyentering 9s in alldenominational .ordersof the machine, except those in whichdigit keysare The result of such .op.eration would be the accumulation in theoverflow order of the .accumulator :of the total number of times thatthe operations control key is depressed to effect a divisioncalculation. Consequently, in order to register a proper quotient in theaccumulator, it is necessary to pre- :vent such automatic entry of 9 inthe .highest denominational order "of the :machine following the firstdepression of the shifter key, and .in each successively lowerdenominational orderfollowing .each subsequent successive depression ofthe shifter key. This object of the invention therefore is attained byproviding mechanism which ismoved .to operative position upon depressionof the division key and which causes each subsequent depression ofthe'shifter key .to efiect depression of the nine digit key in thehighest denominational order of the machine.

Another object of the invention, which is :attained with this samemechanism, is to cause the quotient always to be registered in theleftmost portion or highest denominational orders of the accumulator,with its highest ordinal digit in the overflow order, regardless of theparticular ordinal locationof the dividend in the accumulator.Accurate-andrapidreadingof the quotient by the machine operator is thusfacilitated, and maximum ordinal separation of the remainder therefrommay best be obtained to further insure thegreatest possible accuracy insuch reading of the quotient and the remainder, both during, and uponcompletion of, any division calculation.

A further object is .to improve the keyboard setting shiftingmechanismin such a machine so as to reduce the resistanceofferedtherebyto thedepression of the shifter key by the machine operator.

Another object of the invention is to insure proper operation of themachine in all types of calculations by providing no'vel interlockingmechanisms requiring thatsequence of operation peculiar to-each type ofcalculation 'upon'actuation'of 'theparticular control member thatconditions the machine for use for each particular type of calculation.

Numerous other objects and advantages of the invention will be apparentas it'is better understood'from the following description, which, whentaken in connection with the accompanying drawings,-discloses apreferredembodiment thereof.

In the drawings:

Figure 1 is a top plan view of a calculating machine embodying the-features of the instant invention;

Fig. 2 is alongitudinal, vertical section taken substantiallyon the line2-2 of Fig. 1;

Fig. 3 is a longitudinal, vertical sectiorras seen from the left side ofthe machine and taken substantially on the line .3--3.of Fig. 1, andshowing the several operation control keys;

Fig. 4 is a sectional view similarto Fig. 3, taken substantially on theline 44 of Fig. 1, showing the highestdenominational order of thekeyboard mechanism and the actuator and accumulator mechanisms;

Fig. 5 is a longitudinal, vertical section taken substantially on theline 55 of Fig. 1 at the right side of the machine, and showingthecancelling crank or zeroizing lever and the key-set interlockingmechanism associated therewith;

5a is a detail view of a portion of the mechanism shown in Fig. 5illustrating the connection between the key-set conditioning mechanismand the power trip bar blocking means rendered operative thereby;

Fig. 6 is a transverse sectional view taken substantially on the line -6of Fig. 1, and showing the division control key and associatedmechanism, as seen from the rear of the machine;

Fig. 7 is a transverse vertical section taken substantially on the line7? of Fig. 1, and showing the keyboard mechanism as seen from the frontof the machine from a point adjacent the #1 digit keys;

Fig. 8 is a top plan view of the keyboard mechanism, with parts brokenaway and the key stems shown in section, as seen from a point directlybelow the uppermost key plate;

Fig. 8a is a detail plan view of part of the control mechanism of Fig.8, showing the same in the position assumed with the machine set for theperformance of multiplication or division;

Fig. 9 is a view similar to Fig. 8, as seen from below thesecond-from-the-top key plate, showing the digit key setting shiftermechanism;

Fig. 10 is a plan View, similar to Fig. 8, as seen from the top of themachine with the keyboard mechanism removed;

Fig. 11 is an elevational view of the keyboard and associated controlmechanism, with parts broken away, as seen from the rear of the machine;and

Fig. 12 is an elevational View of the keyboard mechanism, with partsbroken away, as seen from the front of the machine at a point disposedforwardly from the plane of Fig. 7.

Referring more particularly to the drawings, the present invention isillustrated as being incorporated in a power driven, key-responsivecalculating machine generally similar to those of the prior patentsreferred to hereinbefore. As in Patent No. 2,063,962, the calculatingmachine is shown as having an outer casing 25 within which its variousinstrumentalities are mounted on skeleton frame members or partitionplates 22 disposed between the actuating mechanisms of the severaldenominational orders and secured together in spaced relationship atsuitable points by tie-rods 23 (Fig. -2). A plurality of columns ofdigital keys 24, normally held in raised position by means ofindividually associated springs 38. are arranged to extend through thekeyboard, indicated generally by reference numeral 25. The digit keys 24are adapted for depression to determine the digital degree of actuationto be imparted to their associated denominational orders of theaccumulator mecha nism. Each column of keys 24 thus controls therotation of an accumulator actuating pinion 26 (Fig. 2) journaled upon atransverse shaft 27 that extends across the machine and is supported bythe skeleton frame members 22. Rotation of each of the actuating pinions28 is transmitted through an internal ratchet mechanism to a combinedlantern wheel and accumulator gear 28 (Fig. 4) which is also journaledon the shaft 2'1. The gear of the lantern Wheel 28 meshes with acarrying gear 30 journaled on a shaft 29 which is disposed in parallelrelationship to the shaft 27. The carrying gear also meshes with anintermediate gear 3! journaled on a transverse shaft 32, whichintermediate gear in turn meshes with a numeral wheel pinion 33journaled 011 a transverse shaft 3:1 and fixed to a numeral wheel 35.

nominational order of the accumulator for the purpose of imparting adigital unit of actuation thereto each time that a tens transfer is totake place from the next lower denominational order of the accumulator.This mechanism is more fully disclosed in United States Letters PatentNo. 1,357,747 and No. 1,357,748, issued November 2, 1920, and includes acarrying-cam member 35 (Fig. 4) which is given a 180 rotation by asuitable carrying motor spring 31 associated with a carrying gear of thenext lower denominational order for each tens transfer that is to beeffected. The carrying-cam member 36 acts upon a dolly roll secured to abell-crank carrying lever (not shown) to swing the latter in a clockwisedirection, viewing Fig. 4. Such swinging of the carrying-lever causes acarrying pawl 41 4.) pivotally mounted on said lever to throw thelantern wheel and accumulator gear 28 a sufficient distance to impart,through the train of gears, a digital unit of actuation to the numeralwheel 35.

The actuation of each accumulator actuating pinion 26 normally isaccomplished upon depression of a digit key 24 in the correspondingdenominational order by a gear sector 2 (Figs. 2 and 4) meshing with thepinion 28. The gear sectors and the control and actuating mechanism forthem are duplicated for each denominational order of the calculatingmachine, so that a general description of a single set of such mechanismwill be sufhcient for an understanding of all of them. The several gearsectors d2 are rotatably mounted upon a transverse shaft 53, and areadapted to be moved downwardly on an idle or setting stroke to an extentnormally determined by the value of the particular digital key 24 of theassociated column which is depressed. In addition to their function ofdetermining the extent of digital actuation to be imparted to theirassociated gear sectors 42, the digit keys 24 normally act through apower trip mechanism to effect a connection whereby power supplied by anelectric motor, indicated generally at 44 (Fig. 4) through a power shaft45, which is connected to the motor in any desired manner, is effectiveto extend a power spring 45 associated with the particular order withwhich the depressed key is identified. Release of this spring thereafteraccomplishes adding movement. in amount determined by the particulardigital key of the order depressed. Upon depression of said key, thegear sector 42 is moved through its idle or downward stroke by the powershaft 45 into position to impart proper and accurate digit accumulationto the adding mechanism upon its return movement, which is accomplishedby the associated spring 48.

In such normal key-responsive operation of this machine, depression of akey 24 causes its stem 47 to engage a parallel motion bar 48 (Fig. 2)which is pivoted at the front of the machine at 49 and at the rear at 51to levers 52 and 53, respectively, which levers are pivoted in turn uponcross shafts or rods 54 extending through the partition plates 22. Alink 55 is pivotally connected at 56 to the lever 52 and at 5'! to thelever 53. The bar 48, levers 52 and 53 and the link 55 form part of aparallel motion device, and are constructed and mounted as shown anddescribed in Patent No. 2,063,962. Each of the gear sectors 42 isarticulately connected to a hook 58 by a link 59 through a yieldingclutch E3, the hook 58 and the link 59 being articulately connected to asubstantially vertical guide member 60, which, in turn, is pivotallymounted on a transverse shaft 50. Each gear sector 42 also isarticulately connected to a movement controlling bar, generallyindicated by reference numeral 6| (Fig. 4) by a. pin 62 fixed to an armaevatoo.

91 39 t. the gear sector 42. A spring 64 (Fig, 2), attached to lever 53and a tail. piece 65 of a latch: member 68 carried by the bar 55normally con:- tributes toward holdin the parallel: mot-ion device inelevated position, and alsoholdsthe-latchmember 6-6 in a forwardposition for a purpose which will be explained presently; a dog 61:,which is pivoted at B8 onthe parallel motion bar 48 is: provided with alaterally extending lug 59 which is adapted for engagement with. a shelfH on a spring lifted lever 12- pivotally mounted onthe guide member 60'withthe hook 58'. The operation of these. parts is such normally thatupon depression-01in, key 24 its stem- 41' engages and depresses the bar48- to impart motion to the parallel motion device, which carries dog 6?downwardly to depress the lever 12. A spring mounted onthepivot' betweenthe link 59 and tliehook 58 engages the lever 12 and thehook tourgetherear end of the latter ('left end in Fig. 2) downwardly, so that itwill normally cause engagement of the hook 58 with a toothedwheel 3 upondepression of lever 7-2. However, this spring connectionbetween hook 58and lever 72 will. permit movement of the-latter by the dog 61 relativeto the hook, if the hook is restrained in its normat raised position ofFig. 2 in a manner tabelater described. Th'et'oot'hed wheel l3- securedto the power shaft 45; which continuall yturns in acounter-clockwisedirection (viewing Fig. 2 The engagement of the hook 58" with the wheell3pu1ls thel'ink- 59- toward the rear of the machine; or toward theleft, viewing Fig. 2, which imparts downward motion to gear sector 42,through the yielding clutch' 63. Forward motion is thus imparted te'thedigital control bar 61', until one of severallugsprojecting verticallytherefmm,v as wilr be more fully ole scribed hereafter; is stopped bythe stem 41 of the depressed keyfl.

The rearward motion of hook 58- and link 59- causes the guide arm 60 toswing ina counterclockwise directionfrom itsnormal position of Fig. 2'to extend the spring 46 one end of which is connected to: this guidearmand the other end to a transverseshaft extending through thepartition plates 22. The link 59 moves the gear sector 42 downwardly onanidle stroke in re-- sponseto: such swinging. of the guide arm 60 anintoposition to: impart an addingmovement to. the accumulator uponrelease or" the hook 58 anoontr-aotioir of: the spring 46'. The downwardmovement. of gear sector 4'2 nomnally is under the control of the"digital controlbar E l (Fig; 4 and the gear sector is halted when' ithas been moveddownwardly the proper-distance, enabling it upon return:tO-lmpart the degree ofdigital. advancement to the adding mechanismwhichcorrespondsto the particular key 2- 3 de'-- pressed. The yieldingclutchtapermits the continuationi of the rearward movement of link 59; afterdownward movement of the gear sector 42 has been stopped; and until theend of thepower stroke and the automatic release of thehcok 58" fromthe: toothed wheel: 13; The release of hook 513 is accomplishedautomatically in each-- instance, after a set increment of action hasbeen'imparted to the. link 59; by the teethof the wheel 13: Upon thereturn stroke the-opera-- tive stroke) of the gear sector 42 theyielding clutch 63 permits relative movement of the parts in reversedirection to that at the beginning of the adding movement,- andthereafter the adding actuation isiaccompli'shedl It is apparent,there-- fore,- that upon depression of akey 2d, the digital 53-: has anaim: H: which is adapted to engage upon a laterally projecting endi 160f thedog 61? to hold; the dog down against upward return movement and:also to hold the parallel motiondevice in depressed position. Just priorto the release ot the hook 58; pin H in an. upwardly extending arm? T8of the: vertical guide member 60;. which through its. connection withhook 58. has; beer-rv carried rearwardl y, engages a finger T9 of latclrmember 66. and frees the dog 61 so that the parallel: motion device mayreturn tonormal raised-position.

In this. operation; the digit key 2-4 which: hasbeen. operated is helddepressed: until release of the: hook; 58 from the toothed wheel 13,when t the; key will be released and returned to normal raisedlpositionby itslspring 38. A bar 81' (Fig. 2 having rearwardly extending, pointedlocking lugs or teeth 82, isapivoted upon studs Biextending; throughslots at in: bars 48i in each denomi' national. order of the machine.Consequently, upon depression. of a. key 24 the-bar B l is movedrearwardly (to the. left" viewing Fig. 2) relative to the stems. 4.7 ofits associated digit keys 2'5. Referring: more particularly to Fig. '7,it will: be seen that each key stem 47 is. provided adjacent its lowerend with an aperture 85 extending therethrough which is. verticallyaligned with the associated bar 85. (Fig. 6) and into which a-tooth 82enters in: such rearwardmovement of the bar 8t, thus holding the keydown until the parallel motion device is; released and the parts arereturned. tonormal elevated position. It WilL be understood. that no:two digit keys 24 of the same column: ordenominational order may beoperated simultaneously by virtue of a. plurality of anchorshapedlookingmembers. (Figs. 2 and 6)v which are. disposed: betweenadjacent key stems4? in: each. denominational order and are rocked; into locking:engagement with the adia cent keys through: the medium of the apertures85;.upon: depression of: any one key in that order. This keylocking;mechanism is fully describedand illustrated: in United States LettersPatent No; 2043,1121, issued June2, 1936'. Full d'epression. of: anyother key in: the same order, until the depressed key is returned tovnormal position to release these: locking members, is thus prevented.Very limited downward movement of a key." 2-4: is allowed, however, eventhough another key of: that order isin a partially depressed position',for a purpose: which will be explained in detail hereinafter. It willbeunderstood, of course, that any digit key 24 0f one order may be.operated at the same time as any other desired: key of any otherdenominational order or orders.

Rather than! being. key responsive in operation, as above. described forperformingaddition, the instant. mechanism: is optionally operable asakey-set: machine for' the performance of subtraction. problems Themeans for rendering the machine key set for subtractionalso provides forautomatically entering the: tens complement of the sub'trahend' into theaccumulator, sincethe instant accumulator actuator isuni-directionalonly in operation, and this subtraction mechanism is the same as thatfully illustrated and described in my previously cited Patent No.2,410,823. As shown in detail therein, the subtraction control mechanismcomprises a minus control key 86 and an equals control key 8'! (Figs. 1and 3). After entry of the minuend into the numeral wheels 35 of theaccumulator in response to depression of the proper digit keys 24, orwhenever it is desired to subtract some value from that registered inthe accumulator, it is necessary only to depress the minus key 85, setthe subtrahend into the keyboard by depressing the proper digit keys 24,and actuate the equals key 8?. Means are provided, which are fullyillustrated and described in Patent No. 2,410,823, for insuring propersequential operation of these parts by latching or holding the minus keyin depressed position, causing its automatic release upon actuation ofthe equals key 81, and preventing depression of the latter unless theminus key 86 first is depressed.

Upon depression of the minus key 36, a lever 95 (Fig. 3) is swung in aclockwise direction about its pivot 91 to move a pawl 38 carried therebydownwardly, which acts upon a pin !05 in an arm I06 secured to atransverse rock shaft 397 to impart a counterclockwise movement to thisshaft E01. Securely fastened to rock shaft Hll in each denominationalorder of the machine is a lock arm H28 (Fig. 4) which, upon suchcounterclockwise rotation of shaft N21, is adapted to engage anassociated vertical lug HI, one of which is formed on each of the hookmembers 58. The lock arms 168 normally are held in their upperdisengaged position of l by a spring iflfi. But they are maintained inengagement with the lugs HI of the hooks 58 upon depression of the minuskey 8% and until release thereof in response to actuation of the equalskey 8?. While lock arms ms are so engaged with lugs HI, the depressionof any of the digit keys 24 obviously cannot cause engagement of theassociated hook 58 with its rotating toothed wheel ":3, but any digitkey then depressed will be latched and retained in such depressed orkey-set position until released in response to actuation of the equalskey 81. As previously explained, depression of a digit key 24 will causeits associated dog 5! to depress lever '52, and the spring connectionbetween the latter and its hook 58 will enable such operation to takeplace without causing engagement of hook 58 with toothed wheel 73 whenthe hook is restrained by its lock arm H38. However, the depressed key25 will be latched in key-set position by virtue of latch member 56engaging dog 6'! to hold the associated parallel motion device indepressed position, which maintains the associated tooth 82 of its bar8! engaged in the aperture 85 of the depressed key stem. It will thus beseen that those digit keys 24 depressed in entering a subtrahend will bemaintained in such key-set position until their respective hooks 58 arereleased from the lock arms I88 and allowed to drop into engagement withthe toothed wheel 2'3, whereupon the pins 17 will move latch members 65to release dogs 5! and permit spring return of the parallel motiondevices of the depressed keys 24 to normal elevated position.

As in Patent No. 2,410,823, depression or actuation of the minus key 85also renders operative normally inoperative complemental stop mechanismfor subsequently automatically controlling the digital actuation of theadding mechanism in accordance with the nines complemental value of anykey 24 depressed in entering a subtra-hend in all denominational ordersexcept the units order, and for causing the enterof the tens complementof any key depressed in the units order. As previously described, themechanism normally controlling the digital actuation of the addingmechanism in each denominational order comprises the movementcontrolling bar indicated generally by reference numeral 6! (Fig. 4).Each of these bars 6| comprises a regular stop bar I I2 and acomplemental stop bar H3, secured together and spaced relative to eachother by means of studs Hi (Figs. 6 and 10). The bars H2 and H3 haveformed thereon vertically projecting stop lugs H5, the lugs H5 of thestop bar H2 being spaced progressively further back of the key stems 41from the front to the rear of the machine, and the lugs 1 l5 of stop barI I3 being spaced progressively further back of the key stems from therear to the front of the machine (as shown in Figs. 4 and 10). The stoplug H5 of the regular stop bar H2 just to the rear of the 1 key isspaced one step back of the stem of the 1 key, and the distance fromeach succeeding stop lug to its associated key stem to the rear of themachine graduatedly increases until the rearmost lug is spaced ninesteps back of the 9 key. The stop lug H5 of th complemental stop bar H3just to the rear of the 1 key is spaced eight steps back of the stem ofthe 1 key, and the spacing graduatedly decreases until the lug back ofthe 8 key is spaced one step therefrom and the last stop lug is justeven with the 9 key. In the units order, the oomplemental stop bar,which is designated by reference numeral H3, differs from these ninescomplemental stop bars H3 in all other orders in that the stops H5thereon are spaced progressively one step further back than are thestops H5 on the nines complemental stop bar I I3. In other words, thecomplemental stop bar H3 of the units order is adapted to control theentry of the tens complement of any key depressed in that order. Thecomplemental stop bars H3 and H3 are each provided at their forward endswith depending arms H8 (Fig. 4) having a bifurcated portion adapted toembrace the pin 62 located in the upwardly extending arm 39 of theassociated gear sector 42. As has been described hereinbefore, in normalkey-responsive operation, upon depression of a digit key 24 andengagement of its associated clutch hook 58 with its toothed Wheel 73,there is a downward movement of the gear sector 42 in thatdenominational order which, through its connection with the digitalcontrol bar 6!, as just explained, is halted by engagement of theassociated stop lug H5 on the stop bar I 12 with the stem 41 of thedepressed key. The resulting movement is thus just suflicient to addinto the accumulator, upon subsequent release of hook 58 from toothedwheel 13 and return of the parts to normal by spring 46, an amountrepresented by the value of the key depressed.

When it is desired to enter the complement of a subtrahend into theaccumulator during a subtractive operation, the complemental stop barsH3 and H3 are shifted into operative relation with the stems 41 of thedigit keys 24, so that upon depression of a digit key and subsequentdownward movement of the gear sector 42, the complemental value of thekey depressed will be added into the accumulator, as distinguished 13from the actual value of the key depressedwhen the regular stop bar H2is in operative relation therewith. The lower end of the stem of theminu key 86 is provided with an angular surfaceengaging a roll H 8(Figs. 4 and: 10) which is rotatably secured to an upright arm H9.Thearm lit fixedly secured to a rock shaft I2! running from front torear of the machine, and

having a bearing at opposite ends in lateral faces I22 and I22" providedthe upper portions of vertical support pieces HT and H1, which are inturn supported attheir lowerends on tie rods 23. Also securely fixed tothe rock shaft 2! are upright arms 23 and I24 (Rig. 4) located. a jacentthe front and rear of the machine, respectively. The upper free portionof the arm I23 is disposed in a small slotted portion of a.

transverse support bar I25 positioned near the front of the'machi'ne(Fig. 10), which-is slidably mounted in the intermediate frame plates 22and is provided with. a plurality of laterally lac-ed, upstanding pins126 fixedtherein. A similar transverse support bar i2! is mounted. attherear of the machine, which likewise is provided with such upstandingpins 126, and has a:

small slotted portion in which is. positioned the upper portion of. theupright arm. 12 1.. The pins I26 and it? on the bars 125 and I 21,respectively,

are adapted to enter the open. portion between. the stop bars H2 and. H3(or H3) of each of the digital control bars St to maintain. properalignment thereof with. their respective key stems ll. The rock shaftI21. and the support'bars 125 to he rocked to shift the support barsIlli. and

i2? and all of. the digital control bars 6,! (to the left from theirpositions of. Fig.6) to-disposethe stop cars H3 and H3 inoperativerelation with the lower ends of the key stems 41. As seen fromthis figure, thesecomplementalstop bars l 1.3 and Y H3. normally aredisposed in vertical alignment with the slots win the lower end ofthe'key stems il, so. as to he inoperative, but such shifting. upon.depression of. the minus key 85 moves the regular stop bars H2 inwardlyout of alignment with the key stems 4 while moving the complement-a1stop bars into vertical alignment with the inner edge portions of thelower ends of thekey stems.

As fully described in Patent No. 2,410,823,. the minus key to ismaintained in depressed posiwhen actuated, until the equals? key 81subsequently is depressed, so that rock arms the are maintained. inengagementiwith their associated lugs ll! of hooks. 53 topreventengagement of te latter with toothed wheels 13 in response todepression of digit keys 24 in settingv up a subtrahend. The digit keys2-4 depressed in entering the subtrahend are maintained-in suchdepressed or key-set position following depression of the minus key 86,and the parallel mo tion bars of the respective orders of depressedkeys. cannot return to normal position, because:

of the lateral. ends of their dogs. 6'! having; been engaged by theassociated latch members 66,

which remain in such engaged. position until. a power action takesplace, as previ'ously described. Means are provided, therefore, forreleasing the clutch hooks 58, after the subtrahend has been set uponthe keyboard. to enable their engagement with the toothed wheels 73* toallow thecomplement of the subtrahend so set up; to be added into theaccumulator to complete a subtractive calculation. The means foraccomplishing this is under the control of the equalskey 81, the lowerend of the stem of: which engages one arm of a lever 12.8 (Fig. 3)which. is pivoted intermediate its ends one short shaft I31. fixed to anintermediate frame plate; 22. A downwardly extending arm at the rear endof lever (28 is provided with a laterally extending pin adapted for.engagement with the forwardly extending arm of the three-armed pawl 98.Depression-ofthe equals key 81 thus results in clockwise rocking of pawl8% (viewing Fig; 3). to-cause its lower arm to be swung rearwardly to bedmengaged from the pin I95, allowing the shaft. Hi"! to he rockedclockwise under the tension of its. spring lull. The rock arms Mare thusremovedfrom locking engagement withthe lugs Hv formedron. the hooks 58,being returned tov their. normalzposi tions of Fig. 4, thereby allowingthose hooks. 53 in the denominational ordersinwhichdigitikeys 2f;havebeen depressed in the previous setting. f the subtrahend into thekeyboard to dropinto. engagement with their toothed wheels 13.

It is necessary, however, that fls be. added in all denominationalorders in which no digit key 2% has been depressed; and. that. 10 beaddedin the units order if no key has been. depressed therein. This isaccomplished, at. the same time that rock arms I08 are. returned tonormal po sition, upon depression of: the equals key 81 the forward armof. lever [28. engaging a pin [3% fixed in the curved upper end of alever i-Bl to: rock the latter in. a clockwise direction, viewing Fig.3. The lower end of lever I3! is securely fixed to a transverse rockshaft I 38 and is. springurged toward. its rearward or'norma'l positionof Fig.3. Also securely fixed to the rock shaft i38 are a plurality ofupright arms res (Figs. 2, land 6) spaced transversely across themachine; in. each denominational order thereof, the upper extremities ofsaid arms being in engageable relationship. with laterally extendingpins Hi: mounted in. the links 55. Depression of the equals key 8'. thusswings the upper ends.' of all of the arms 39 forwardly to urge thelinks 55 in 'a forward; direction. Movement of any of the links 55 inthis manner imparts motion to theassociated parallel motion device, inthe same mannor as though caused by depression of a digit key in thatdenominational order, to cause depression of hook 58 controlled therebyinto the path: of its associated toothed wheel '13, which results in anadding actuation; in that denominational order. Movement of the parallelmotion device, however, not having resultedfrom depression of digitalkey 24 in such order, itwill be apparent that bar iii which controls thedigital setting. of the gear sector (i2 will receive afull forwardmovement, with a consequent maximum down ward movement of the gearsector sufiicient to add 9 into theaccumulator upon the upstroke of thesector under tension of spring it. When. no key has been depressed inthe units order, that is, when a zero occurs inthe units order of thesubtrahend, forward swinging of the arm I39 therein likewise will causemaximum downward movement of the gear sector 42, but the resultant 15upstroke by the spring 46 will add 10 into the units order of theaccumulator, rather than the 9s added in the other orders in which nokeys were depressed.

In machines of this type, it is customary to provide an overflow numeralwheel, indicated at I50 in Fig. l, to which is transferred the carry ofthe 10s resulting from operation of the actuating mechanism in the lastor highest denominational order. The instant machine provides actuatingmechanism in the overflow order for automatically adding the value of 9to the accumulator mechanism of that order to bring to zero position thenumeral wheel iB when a 1 has been carried thereto by the entering ofthe complemental value of the subtrahend and the subsequent carrying ofthe s across the register, as just described. To this end, there isprovided a gear sector 242 (Fig. 3) similar to the sectors 32 alreadydescribed and mounted on the shaft 43, but directly connected to a guidemember 2230 by means of a link 258 which is pivotally interconnectedbetween sector 232 and guide member 2539. A spring 245, similar to thesprings 46, is connected to this overflow guide member 258 to maintainthe latter and the gear sector 242 in their normal position of Fig. 3.Rearward movement of the guide member 255 thus will cause downwardmovement of the gear sector 2&2 in an idle or setting stroke, and thespring 248 will return it to normal raised position in an addingmovement in manner previously explained relative to is regular sectors42. Such rearward movement of the guide member 252 is accomplishedthrough connection with the guide member 60 of the next adjacent orhighest denominational order. keys 8% and 3'! are provided with a shortmodified parallel motion device, similar to those in the severaldenominational orders previously described, which includes a link 2555(Fig. 3) having a pin M8 fixed therein. Depression of the minus key 85?thus cause forward movement of this link 255 and its pin I48, and thelatter rocks a spring urged lever [48 clockwise (viewing Fig. 3) againstthe action of its spring to depress the rear end of a hook or look piece154, which is pivotally mounted on a horizontal arm I5 5 of the guidemember 250 of the overflow order, so as to engage this look piece 54with a pin l5! secured to the guide member iii? of the next adjacent orhighest denominational order. Upon engagement, therefore, of hook member5-8 with toothed wheel 3 in this highest denominational order to theright of the overflow order, either resulting from the setting of a.digital key 24 therein and/or depression or" the canals control key 8?and release or" look arms its as previously explained, the guide men her6!. in that order will be pulled rearwardly and, by such connection withthe uide member 28 of the overflow order through lock piece i 54, thegear sector 242 of the overflow order will be given a maximum downwardmovement to add 9 upon its subsequent upward movement under the actionof the spring 2 26. Such rearward movement of the overflow order guidemember 260 will release the parallel motion mechanism in the overfloworder to enable automatic return of the keys 8% and 8'? in the samemanner as the parallel motion devices in the other orders of the machineare released, as previously explained. A subtractive calculation thus isoompieted upon the depression or" the equals key 8?, and the severalparts moved to operative position by the previous depression of theminus key automatically are returned to inoperative position to resetthe machine for normal key-responsive operation.

Addition and subtraction problems thus are performed with the instantmachine in the same manner as with that of Patent No. 2,410,823, and thereference numerals so far referred to herein are the same as thoseemployed in Patent No. 2,410,823 to designate similar parts. On theother hand, problems of division and multiplication are performed on thepresent machine by means of mechanism different from that disclosed inany of my prior patents hereinbefore referred to, and in the case ofdivision, in an entirely different manner. To perform a problem indivision, after entry of the dividend into the accumulator, a divisioncontrol key 39! is depressed which moves the complemental stop bars H3and HS into operative position, in the same manner as does depression ofthe minus key 86, and also conditions the machine for subsequent key-setoperation, but not by means of the lock arms IE8, which remaininoperative. Instead, depression of key 33! moves a normally inoperativeordinal slide bar in each denominational order into an intermediateoperative position to positively limit the extent of downward movementof the digit keys 24 thereafter depressed to set up the desired divisorin the keyboard. Any keys 24 depressed to set up the divisor areretained in such key-set position by ordinal key-latching bails likethose in my prior Patent No. 2,436,574, but the ordinal slide barsprevent such setting of the digit keys from effecting operation of theaccumulator actuating mechanism and limit downward movement of the keysto a degree only sufiicient subsequently to control the extent ofmovement of the gear sectors 42 in the associated denominational ordersby limiting movement of the complemented stop bars H3 and H3. Subsequentdepression of an operations key will effect engagement of all the hooks58 with their rotating toothed wheels '53, through the agency of theoperations shaft 38 and the rock arms I39, to cause operation of all ofthe gear sectors 42, but not of the gear sector 242 in the overfloworder. The result of each such depression of the operations control key,therefore, will be to enter into the accumulator the nines complement ofeach digit key 24 depressed in setting up the divisor, except in theunits order in which the tens complement of any depressed key will beentered, and to enter in each denominational order in which no digit keyhas been depressed and 10 in the units order, if no key has beendepressed therein. As a result, the overflow numeral Wheel I50 willregister 1 and the remaining orders of the accumulator will register theintermediate remainder, comprising the dividend with the di visorsubtracted from its corresponding highest orders, the divisor initiallyhaving been set up in those denominational orders of the keyboardcorresponding to the highest denominational orders of the accumulatorcontaining the dividend where such ordinal values of the dividend areequal to or larger than those of the divisor. The operations control keythen is repeatedly depressed until the crdinal values registered in thedenominational orders of the accumulator corresponding with those ordersof the keyboard in which the divisor is set are thereby reduced to lessthan the divisor. Each such depression of the operations control keywill result in the addition of l to the registration of the overflownumeral wheel 15s. The keyboard setting of the divisor then is shiftedautomatically one denominational order to the right by depression of akeyboard setting shift key and, if the ordinal values registered in thecorresponding orders of the intermediate remainder" equal or are greaterthan the divisor, such previously described actuation of the operationscontrol key is repeated; or if such values of the corresponding ordersof the intermediate remainder are less than the divisor, the shift keyis depressed again. These operations are repeated until the remainder isless than the divisor. If, as is normally the case, the dividend wasentered in the lowermost denominational. orders of the accumulator, thefinal result of such division operation will be the registration of theuotient in the highest denominational orders of the accumulator, withits highest order digit being indicated by the overflow numeral wheel .5and with the remainder, if any, being registered the maximum possibledistance therefrom in the lowest denominational orders of theaccumulator.

Referring particularly to Figs. 1, 3, l, 6 and 10, the division key Sillis located to the left of the highest denominational order digit keys 24in front-to-rear ali nment with the keys as and 8'5. The lower end ofthe stem of key at has an angular portion (Fig. 6) in engagement with aroll (Figs. 4 and it) rotatably secured to an upright arm H9, similar toarm H9 previously described, and likewise secured at its lower end tothe rock shaft iili. Depression of key Sol thus shifts all of thedigital control bars 6i laterally, in the same manner as does depressionof the minus key 85, to move the complemental stop bars M3 and H2 omtheir inoperative to their operative positions relative to the digitalkey stems ii. In order to maintain the division key Eel in depressedposition during the subsequent operations performed in a divisioncalculation, as above described, a vertical latch or look lever 3%(Figs. 3 and 6) is provided which is substantially identical to thelock: lever 385 employed in my prior Patent No. 2,492,703. This locklever 33 4 is pivotally mounted at its lower end at and urged in acounterclockwise direction (viewing Fig. 3) by a suitable spring 3235.The upper end of the lock lever 395 is provided with a rearwardlyextending projection 35! having an angularly disposed upper surface, andan outwardly displaced cam finger 3&8, these portions of the lock leverbeing similar to the projection 332 and cam finger 3&3 of the lever ofPatent No. 2,492,703. As best seen in Fig. 6, the outer, lower end ofthe stem of key 3M is cut away to a point just above the upper end ofthe lock lever 354, and this key stem is provided with a pair ofvertically spaced aperture see, similar to the apertures in the digitalstems M, which are aligned vertically with the lock lever 364. Thus,depression of division Full causes the bottom surface of its key stem toengage the angular surface of the projection as! to swingthe lock leverin a clockwise direction (viewing Fig. 3) against the action of itsspring 366, and complete depression of the key till permitscounterclockwise return of the look lever 304 by its spring to normalposition which engages thenose portion of the projection 33'! in thelower aperture 369 to prevent upward return of the key 301. As best seenin Fig. 6, the key 30! is pro-- vided with a spring 38 similar to thoseassociated with each of the digit keys 24 for normally urging the key toits raised position. Intermediate its ends, the lock lever 3M normallyengages in a flat or notched portion of a transverse shaft 3!! which issimilar to the shaft 343 of Patent No. 2,492,703. This shaft 3i i, aswill be more fully explained hereinafter, is rotated upon depression oractuation of either a release .key or the zeroizing lever, and suchrotation of the shaft will rock the lock lever against the action of itsspring 3% to release the proection sill from the aperture 3&2 to permitreturn of the division key till to its normal upper position by itsspring At the same time, the cam finger sea on the lock lever 3% willengage the lower end of the stem of key 3! when the projection 36'! isremoved from the aperture 399 to cam the key 30! upwardly, if there isany tendency for the key to stick or bind.

As in Patent No. 2,430,524, the keyboard 25 herein comprises a controlunit mounted on the vertically disposed skeleton plate 22 above theaccumulator actuating mechanism, and it includes five substantiallyhorizontal frame plates numbered 5H2 through 316, from bottom to top or"the machine (Fig. 2), in parallel spaced relationship. The threelowermost keyboard plates 3&3 and Ei-l are mounted on the skeletonplates 22 as in my prior machines and are suitably slotted, not only toreceive and guide the various key stems, but also to retain the anchorlocks therebetween, and the springs 38 are mounted on suitable lugsstruck up from the plate 313. The remaining parts of the keyboardmechanism, to be described hereinafter, are mounted between the middleplate 314 and the added two top plates 315 and BIG, plate 2H5 beingsecured to, and spaced from, plate 3 by suitable threaded spacingcollars secured to the latter and screws 3|? (Fig. 8). Transverselyextending angle bars 318 and Bill (Figs. 2, 8, ll and 12) are disposedacross the front and rear edge portions, respectively, of plate 3H3 andare secured thereto in any suitable manner, as by means of screws 319and 319' (Fig. 3). A plurality of angle brackets 3221 (Figs. 2, 6, 7 and8) have their horizontal feet secured in any desired manner to the underside of the top keyplate 316 and are aligned from front to rear of themachine in groups of three, with the de pending vertical legs of thefront and rear end brackets of each group slidably engaging the innersurfaces of the vertical faces of the transverse bars 318 and 358'.These vertical faces of the bars EMS and dill and brackets 32! areprovided with suitable aligned apertures for receiving rods or shafts322 which thereby retain the upper keyplate Sit in place and preventlateral movement thereof, one such rod 322 being provided for each suchgroup of three brackets 32!. The end brackets 32] in turn preventfront-to-rear movement of the keyplate SIB. As shown in Figs. 2 and 8, atransversely extending bracket 323 secured to the keyplate 3i5,

by means of screws 324, is provided with upstanding apertured ears orlugs S25 adjacent each of the intermediate brackets IEZI for receivingthe rods 322 to secure the central portion of the upper keyplate Sit.The bracket 323 also is formed with rearwardly extending curved fingers326 for receiving a transverse rod or shaft 32?, for a purpose presentlyto be explained. As best seen in Fig. 2, removal of the various digitaland control keys from the keyboard will permit lifting and removal ofthe top keyplate 3i3, upon rearward. withdrawal of the several retainingrods from their engagement with the angle bars and 3l8', brackets 32%and ears which may be accomplished following removal of the casing 2i ofthe machine.

In addition to rendering the regular stop bars inoperative and thecomplemented stop bars H3 and H3 operative, as previously described,depression of the division key 3M also renders the normallykey-responsive instant machine key-set, so that any digit keys 2&subsequently depressed to set up a divisor in the keyboard will remainlatched in a partially depressed position. The mechanism now to bedescrib d for rendering the machine key-set is not that renderedoperative by depression of the minus key since actuation of key 356 doesnot rock shaft to engage lock arms with lugs ill of the hooks but itincludes ordinal ke latches somewhat similar to the key latch bars 114of Patent No. 2,430,574. One of these latches i is provided in the formof a longitudinal bar or bail in each denominational order of themachine adjacent, and at the ri ht side of, each row of stems t? of thedigit keys 2:; (Figs. 2, 8, 6, '7, 8 and 8a). Each latch bar or ball isjournaled for pivotal movement on suitable trunnion studs, formedintegrally tierewith at each end adjacent its upper edge, which extendthrough apertures provided in the vertical portions of the front andrear transverse angle bars 313 and Git. Formed on each latch bar are aplurality of depending latch each terminating in an inwardly exiower endadapted to engage below, be carnmed outwardly by, or engage above aprojection Edi formed on each of the stems ll of the digit keys 24 (Fig.'7). As best seen in Figs. '7 and 8, the latch arms 329 of each bar orbail 328 are urged toward engagement with their associated digital keystems 4? by a spring connected between the forward arm 325 and a studpin 332 secured to, and upstanding from, the keyplate Adjacent the rearof the machine (Fig. 8), a transversely extending bar 334 is slidablymounted on the keyplate 3i5, by means of suitable pin and slotconnections, which is provided with a forwardly and upwardly extendingfinger or projection 335 in contacting relation with the rearmost arm323 of each latch bar 328 (Fig 8a). The left end of this bar 334 isurged by the several latch bar springs 332, through the agency of therearmost arms 329 of the bars and the fingers 335, outwardly intoabutting engagement with a pin 333 upstanding from he rear of a bellcrank lever 33'! pivotally mounted intermediate its ends at 338 on thekeyplate 3l5. The other arm of lever 33'! is provided with a similarupstanding pin 339 engaging in a vertical slot in a stud 3 1! secured tothe inner side of a longitudinally extending link 342. At its forwardend (Figs. 3 and 8) this link 342 is pivotally connected to thedepending arm of a bell crank lever 343 which is pivotally supportedintermediate its ends at 344 by a suitable bracket 345 extendingupwardly from the keyplate 3i5. The rear end of the other orsubstantially horizontal arm of the bell crank lever 343 is disposedbelow and in engagement with a shoulder formed on the stem of thedivision key 39! by means of a cut-out portion 346 provided in the outeredge of this key stem, as best seen in Fig. 6. In-

28 termediate its ends, the link 342 (Figs. 3 and 8) is provided with anoutwardly extending stud 34'! to which one end of a coil spring 348 isconnected, the other end of this spring being anchored to the keyplate3l5 by an upstanding stud pin 349.

When the machine is in its normal key-responsive condition with thedivision key 3M raised position, the spring S ll) maintains the link342, bell crank lever 33? and transverse bar 324 in their positions ofFig. 8, wherein the fingers 335 maintain the several latch bars or bails328 in their inoperative position of Fig. 6. As therein illustrated, thelatch arms 328 thus are maintained out of operative association with theprojections 33l on the digital key stems 41. Upon depression of thedivision key 33!, however, the rearwardly extending arm of bell crank343 is depressed by the shoulder of the key stem to move the link 342forwardly against the action of spring 348, which swings the bell cranklever 33! from its position of Fig. 8 to that of Fig. 8a. The springs332 of the several ordinal key latches 328 thereby are permitted toswing the latch arms 329 from their position of Fig. 6 to that of Fig. 7to engage their lower ends with the digital key stems 41 below theirlateral projections 33L Subsequent depression of any digit key 24 thusresults in its associated latch bar or bail 328 being swung outwardlyagainst its spr ng 332 by the resulting cam action of the projection 33!against the lower end of its associated latch arm 323. Continueddepression of the digit key 24 in sufficient degree to dispose theprojection 33! below the lower end of the latch arm 329 will permitspring 332 to return the latch bar 328 to its active position of Fig. 'lwith the lower end of the latch arm 329 disposed above the projection33: to retain such depressed digit key against return upwardly to normalposition by its spring 33. Obviously, if any other digit key 24 in thesame denominational order subsequently is depressed while such firstdepressed digit key is so retained in partially depressed position byits latch bar 328, the latter will be released from latching engagementwith the projection 33! of the first depressed key to permit returnthereof by its spring 38. Such depression by another digit key in thesame denominational order in which a previously depressed key is latchedin partially depressed position is permitted, as previously explained,by the upper slotted portion or the apertures 35 (Fig. 7) in the digitalkey stems 42'. This slotted portion of each aperture is of sufficientlength to enable depression of a digit key to the point at which itsprojection 33l will release the associated latch 328, to permit returnof any other key in the same order previously latched in partiallydepressed or key-set position by its latch arm 329, efore actuating theadjacently disposed anchor locks 90, which the key stem does thereafterin the lower portion of its movement to key-set position.

Depression of the division key 362, as well as rendering the instantmachine key-set, also renders mechanism operative to positively preventmachine actuation in response to subsequent depression of any digit key24. This keyblccking mechanism comprises a normally inoperative ordinalslide bar 35E mounted in each denominational order of the machine andextending through vertical slots 352 in the associated key stems 41(Fig. 7). The forward end of each of these ordinal slide bars Bill isreduced

